Residual impurities in high purity GaAs layers grown by liquid phase epitaxy in H 2–Ar atmosphere

Abstract

We have carried out LPE of GaAs using Ga as a solvent in high purity Ar and its mixture with H 2. The quality of the layers was compared with that grown in pure H 2. The layers grown in Ar showed n-type conductivity. Net carrier concentration and mobility were 3×10 14 cm −3 and 4×10 4 cm 2 V −1 s −1 at 77 K which is comparable to that for the layers grown in H 2. Photoluminescence measurements reveal that Si is the main acceptor impurity in GaAs layers which were grown in H 2 atmosphere. In contrast, C is the main impurity in the layers grown in Ar atmosphere. The impurity incorporation into GaAs layers can be ascribed to the chemical reactions that take place during the LPE process in the growth system which consists of quartz reactor tube, graphite crucible, and Ga solvent.